Résumé
This study was intended to clarify factors that contribute to swimming performance, and to determine the extent to which these factors change with respect to junior swimmers' development. Participants were 114 boys and 130 girls, 8-18 years old, who belonged to swimming clubs. They were classified into four groups : 8-10 years, 11-12 years, 13-14 years, and 15-18 years. We selected four factors - body size, muscle strength, flexibility, and stroke efficiency - which are putatively related to swimming performance. Swimming performance was identified as standardized 50 m records. We applied simultaneous analysis of multiple groups to multiple regression models and thereby examined the relationship between those four factors and swimming performance with respect to age and sex.Stroke efficiency was the salient explanatory factor for swimming performance of swimmers of both sexes under 14 years. For the over-15 age group, muscle strength was the most effective parameter in boys, whereas body size was the most influential factor of swimming performance in girls. The influence of swimming career was small. These results suggest that stroke efficiency contributes strongly to the swimming performance in subjects who are less than 14-years-old, but that body size and muscle strength do not. For swimmers over 15-years-old, stroke efficiency was less important, but muscle strength was an important explanatory factor of swimming performance.